


What Lies Beneath the Waves

by crimsonflowerss



Category: Fire Emblem: Fuukasetsugetsu | Fire Emblem: Three Houses
Genre: Alternate Universe - Creatures & Monsters, F/F, One Shot
Language: English
Status: Completed
Published: 2020-03-20
Updated: 2020-03-20
Packaged: 2021-02-28 01:53:31
Rating: Teen And Up Audiences
Warnings: Graphic Depictions Of Violence
Chapters: 1
Words: 4,060
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/22945828
Author URL: https://archiveofourown.org/users/crimsonflowerss/pseuds/crimsonflowerss
Summary: “The sea was a place of solace and refuge, but it was also one of constant change and turmoil.”-A lone siren on the verge of death after a close encounter, a princess of dragons who finds and heals an injured woman on the shore, and the longing of two different people from two different worlds. How far would you go to save the person you didn’t know you’d love the most?-A mythological creature AU one shot
Relationships: Dorothea Arnault/Petra Macneary
Kudos: 24
Collections: Doropetra Week 2020





	What Lies Beneath the Waves

The sea was a place of solace and refuge, but it was also one of constant change and turmoil. Those are the reasons why Dorothea Arnault both loves and loathes her circumstances of being a denizen of the ocean. For one thing, she was inhuman. Literally. Dorothea was a siren, a being whose songs are ethereal and entrancing, but if one listens to their melodies for long, they’ll be lured and meet a most unfortunate fate. 

There had been rumors from sailors of the coast of the Empire of a mystical songstress that relentlessly kills many of the men aboard their galleons while somehow, if women were present, they would be spared. Many of the ships caught up in these rumored assaults would end up being covered in blood and the decaying parts of crew members who lost their lives and ended up being a meal for this beast. And for that reason she was constantly persecuted by those from the land, humans who would get any chance they would get to claim the bounty of such a beast. Dorothea believed that she wasn’t the monster in the story, but rather the humans themselves. They were the ones who caused her to be orphaned. They were the ones who persecuted her for her mere existence, despite the relative harmony that was established between humans and creatures such as herself. But she was only doing this to survive. It was a primal instinct to crave human flesh as it is for a siren. 

The waves began to rise higher than usual due to the howling ocean winds. Trying to view her surroundings while the sea sprayed in her eyes, Dorothea was on her guard. Although there was a minor nuisance of her hair blowing frantically from the currents, she was still alert. So far, there were no signs of those willing to capture or kill her. She retreated back into the depths below and continued to swim further into the ocean. Beneath the waves it was eerily silent. Usually the sounds of the waves above would loudly echo down below, but yet there was no sound. Something was wrong. Once more, she ventured to the surface of the waves and began to unfurl the wings upon her back. Sirens were known to be beings of both the sea and skies, but unlike her others of her kind, Dorothea rarely took flight. This time it was different. She was on high alert and instinctively knew something was amiss. And suddenly the whirling of an arrow sounded quickly past her. She wasn't alone. There were humans after her. And they wanted her dead.

“Gather our men on deck! We have a siren to catch and a bounty to claim!” one of the sailors shouted. The ship they were on board was clearly and distinctly from Enbarr, but they were not official imperial troops. They seemed to be mercenaries and sailors setting out on one specific journey and that was to find Dorothea and to prove that those rumors of something beneath the waves were true.

 _Not now. Please, not now._ The siren thought to herself. She tried to hold it back the moment she spotted the humans from afar, but now she wasn’t able to control herself. She was hungry and the taste of flesh was too good of an opportunity to pass up. Her heart started to pulsate faster than normal, her head began to throb. There was no use trying to control it any longer. She emerged from the ever-changing tides with wrath and fury in her eyes. But from her mouth, she began to sing a seemingly irresistible melody. Her deadly aria reached the ears of the unsuspecting crew and almost instantly they became entranced. All except for a select few who were somehow covering their ears for precautionary measures that included the captain and a couple other men who were reading their nets and harpoons to strike at the siren. But for some sailors, it was too late. The sea began to turn from murky blue to a faint crimson as blood seeped into the water. They already succumbed to her song by jumping off the deck of the boat and brutally impaling themselves with their spears and blades, covering their vessel in red in the process. This was the deadly power a siren held and Dorothea only used this ability when absolutely necessary. 

“Don’t give in to ‘er call! Grab the nets! Let’s end this sea witch’s terror once and for all!” one of the survivors shouted from afar. Suddenly, her singing halted as she began to continue making advances on the unsuspecting humans above her. The men thought that she had retreated back into the depths, and that was exactly what Dorothea wanted. They were lulled into a false sense of security but yet stayed vigilant. She was rearing to strike, silently unfurling her feathered wings and rearing her sharp fangs. As it was before it was quiet. A bit too quiet. Then, out of the ocean's shadows, she flew up to the deck without the crew noticing her and mauled a man holding a spear, piercing his neck with her fangs and biting down hard as he suffered a quick and painful demise. Her eyes seemed to glow in the midst of the carnage as she feasted on the fallen sailor. From her flank, another man began to charge at her with a harpoon but she swiftly kicked him off the boat into his watery grave. This is what she was dreading: her primordial, predatory instincts taking all control over her senses. She could only focus on feeding herself and satiating her instinctive bloodlust. But what she wasn't focusing on was the captain of the galleon readying to fire an arrow directly into her chest. 

She only noticed it in time to dodge her heart from getting pierced with the steel arrow, but at a cost. Instead of the trajectory being focused on her chest, the wind made it difficult for the captain to fire a straight shot. It hit one of her wings and damaged it severely. Wailing out in pain, she tried to strike back at the captain but Dorothea was too late. Blood began to profusely flow out of the bone marrow and flesh of the feathered wing. She couldn't control her sense of direction, not after being so severely injured. The siren gave up trying to fight back against her pursuers. She began to fall quickly into the salty seas below. The battle was over, but at a cost. She had her meal, but she almost lost her life. Dorothea had little strength left to swim to safety. She was covered in wounds and gashes not just on her wings, but on her scaled and finned legs and body as well. Her heartbeat began to die down after the frenzy due to the immense loss of blood. Dorothea began to lose consciousness slowly as she tried to brave the currents. 

_Please...not now... I don't want...to die like this._

She closed her eyes for a brief moment. She continuously tried to swim off the pain, but to no avail. She gave in to the tide's flow. And everything went blank. 

* * *

When Dorothea slowly reopened her eyes, she was not in the midst of the aquatic blue yonder. Her face and body lay on the shores, off the coast of a seemingly uninhabited island. Slowly getting up, she began to survey her areas but not soon after she fell back down to the sand because her strength was still waning and recovering. But she noticed something off. While the rest of her body ached, there were no scars present as they were before and her wings felt rejuvenated as well. Miraculously she had been healed. But at the same time, the lack of life on the coastline wasn't giving her any ease as to how she had recovered. Dorothea began to call out into the vast shore because she believed that was the only thing to do.

"Hello? Is there anyone out there?" No response. Not giving up yet, she tried again, calling out once more into the vast unknown.

"Please! Is anyone here? Hello?" There still was no sound, except for the wind rustling against the forested palm trees in the distance and the waves crashing on the sandy shore. But then the rustling increased in intensity and Dorothea instinctively staggered back near the water's edge. From the forest ahead, she could see something, no some _one_ emerge carefully from the bushes. It was a woman. 

But the thing that stood out about her was the fact that she didn't look human. Not fully, at least. Her body and face was slightly covered in iridescent magenta scales that shone whenever the sun reflected off of them. Long and braided burgundy hair trailed behind her. Her ears were slightly pointed and finned, somewhat similar to Dorothea's own, and behind them portruted medium-sized horns that looked oddly similar to coral branches. From her back, there was a long and scaled tail with the same reflective scales that were embedded on her skin. The woman was wearing an elaborate outfit that appeared to be made out of hand-dyed fabric and leather adorned with a multitude of accessories including necklaces, beads and colorful patterns. On her face and arms were simple yet elegant tattoos. To put it simply, she was stunning. And Dorothea was staring directly at her. The other woman began to slowly walk up to her, docking her head somewhat inquisitively. 

"Are you being alright?" she spoke. Dorothea was still somewhat infatuated, and tried to get back on track as to what the woman was actually saying.

"Yes...Oh, yes. I'm fine. Thank you for asking." the siren responded. 

"When I was first seeing you, you were covered in scars and wounds. I could not bare to see someone lay on the shore and suffer, and so I was healing you." It then clicked for Dorothea. This woman was the person that saved her life. The reason that she didn't end up dead on some seemingly deserted island. She was the one responsible for her miraculous recovery.

"Thank you. You really didn't have to, though." Dorothea hesitantly replied.

"Why are you saying that? If you had not been healed then your pain would be getting worse. It is truly fortuitous that you were still breathing and that you had not died when I arrived. Your wounds were being severe, and I am being thankful to the spirits who have guided me to you." The woman seemed to be genuine in her response. To have the kindness to save a stranger was a quality that was rare to come across, especially in those who weren't human. The only other person she’d know to have this type of generosity was another siren who’d previously took her under her wing and taught her the hauntingly beautiful melodies she knows to this day, but in her mind she’d known that she’s probably far gone. “I am wanting you to come with me. It would be safer if you would not stay on the shore.” The woman reached out her hand towards Dorothea and tried to lift her back on her feet once more. Her legs and body still ached but holding on to her made her feel at ease. 

“What’s your name?” Dorothea finally asked her.

”I am being called Petra Macneary. And what should I be calling you?” She responded.

”Dorothea.. Dorothea Arnault. I guess now’s a good time to properly thank you since I just learned your name, Petra.” As she was saying this to her, she couldn’t help but feel the warmth and comforting touch of Petra’s scaled hand. Being a siren meant that you were always on the move and constantly on guard so there wasn’t much time for having tender moments such as these. Her face began to feel slightly flushed and her heart began to race, but she wasn’t hurt or anything. What was this feeling? 

“So, where exactly are we going?” Dorothea asked Petra as they walked from the soft sands of the shoreline to the leaf covered undergrowth of the forests that stood in front of the waves. She had never been on land for this long and she started to instinctively worry, but internally she knew she was going to be safe with Petra’s guidance. 

“In time, you will see.” Petra responded. As they continued walking for a few miles, the two of them could see a large clearing in the middle of the lush thicket. There were clear signs of habitation including makeshift houses on the ground and shelters up in the treetops, areas where others could convene such as open stone fire pits and waterfalls that flowed into much smaller pools. And the obvious fact that there were other people that looked exactly like Petra in the clearing as well. Dorothea could feel their judgmental gazes from a distance. They seemed wary of her, staying away from her as far as possible. Maybe they viewed her as a bad omen much like the humans that persecuted her as well. But that seemed to not be the case with Petra. 

The place that she was leading her was a large cavern with torches lighting the walls. Other people seemed to be awaiting Petra, but not Dorothea. Water seeped through many of the cracks and crevices and in the center was a small yet deep basin that was the result of the continuous flow. The walls appeared to be covered in paintings and markings somewhat similar to the ones on Petra’s body and face. As the siren and the stranger slowly walked into the cave, the others bowed solemnly as if to say “welcome home”. Petra seemed accustomed to all of this, meanwhile Dorothea was still utterly confused. 

“Petra, is there something you’re not telling me?” Dorothea quietly asked. Soon after, Petra’s pointed ears perked up and she suddenly realized that she had forgotten something crucially important.

“Oh! I was to tell you this earlier. I am the daughter of the ruler of this island. In other words, I am the princess of Brigid.”

Dorothea stared at her in complete and utter shock and silence. The person who saved the life of a commoner siren, one who was notorious in the waters of Adrestia for acts of bloodshed against unfortunate humans who strayed into her path, turned out to be the princess of an island nation that she didn’t know existed. Dorothea had previously encountered nobles underneath the waves, but they only saw her for her beauty and she rejected most of her suitors' proposals, even if they tried to hurt her in response to her rejection. She was confused as to why she would do such a thing, but yet eternally grateful all the same. But soon enough the silence was broken as from the corner of her eyes she could see water from the crystalline pool in front of her rise and a large shadow that was submerged underneath ascended. A massive draconic creature with opalescent dark blue scales and glowing markings emerged and gazed at the presence of Dorothea and Petra. The beast soon shifted into a human-esque form wearing similar elaborate clothing like Petra, despite the obvious fact that he was an older man and was wearing many more adornments compared to her, but in a sense you could tell that he and Petra were related because of his gray hair that had muted purple undertones. He stared unflinchingly at the two women who stood in front of him.

“ _My granddaughter, you have returned.”_ the man spoke. Dorothea could not understand what he was saying but she soon realized that he was speaking in an unfamiliar tongue. 

“ _I have. I am sorry if I have worried you so. I hope you understan-.”_

“ _You know you are not to bring outsiders into the midsts of our territory. If it had been a human, then there would have been slaughter like the wars that plagued us many moons ago. But it appears not to be so. The outsider you have brought may be of the sea and sky, but you must still stay vigilant.”_

_“The spirits told me she was injured on the shore. If I...if they had not intervened, then she would’ve died. Grandfather, I believe there is something truly special about her. I wish for you not to pass your judgment.”_

_"Very well. If the spirits have guided you to her, then it shows that her life was worth saving. I am placing her under your protection, but you must remember to stay on your guard. This woman is a siren after all, and lulling people into a sense of idyll is what they do best. Do I make myself clear?"_

Petra slowly nodded in response to her grandfather's proposal. He then began to speak to Dorothea. 

“My granddaughter will be showing you our ways. It is rare that we mo'o ever let outsiders into our land, but you are of the sea and sky so you can be trusted. For the time being, at least. You were rescued for a reason, and I wish to see why." he said. 

"Thank you for your generosity, sir. I mean your highness, assuming you're the king, right? But in all seriousness and formalities, I am truly grateful for you allowing me to seek refuge here." Dorothea replied while taking a small bow. She looked back at the mo'o princess, who flashed a quick smile. She could see her slightly fanged teeth and she couldn't help but blush. It'd been quite some time since Dorothea had seen anybody act this genuine towards her. She seemed so... happy. Ecstatic even. Maybe her rescue _was_ preordained by the spirits, even if she didn't believe in them. Even still, she had to get accustomed to life on land despite the fact that she had legs. 

Petra reached out her scaled hand and gestured toward Dorothea to come forward & follow her lead. She took her hand once more and there was that feeling again. The feeling of warmth and comfort emanating from just a single person was one that she could get used to as she was basically accustomed to being alone in the cold depths. The mo'o princess took her out of the cavern from where they were before into what seemed to be the central square of the village. In it was a multitude of commodities that were usually seen in human settlements, but the architecture and stylization were unlike any she'd seen before. The houses and additional structures were simple yet complex because they included intricate carvings on the foundations whilst also being made out of common material found in the surrounding forests and beaches including stone bricks made out of mud, wood from trees and driftwood that ended up stranded on the shores and occasionally giant palm leaves that provided extra shelter from the sweltering island heat. Dorothea didn't have the time to appreciate every minute detail that was in the surrounding village when she was first brought here, but since she now had nowhere else to go she couldn't help but acknowledge them. She was so used to being alone that she'd forgotten the feeling of company. Petra continued onwards until she stopped at the area where she first arrived and guided her towards the pool of water, assuming that she was still unaccustomed to being on land. It was a temporary sanctuary for her. Once more, she was unused to anybody being this hospitable towards her despite a few exceptions. She slowly started to climb into the shallows, the feeling of the cool water stinging her wounds somewhat, and started to feel at ease again. Petra, however, started to climb a tree and soon perched upon it whilst laying back comfortably. Dorothea could never be as adept or agile in her arboreal surroundings as her so she stayed in the shallows. She sighed deeply.

"Petra... can I ask you a question?" The siren pondered. Quizzically, the mo'o looked down.

"You may."

"I was just wondering... _why_ exactly did you save me?"

Petra soon went silent and hesitated in her response. "As I was telling you before, the spirits guided me to you. I also did not want your wounds to be getting more severe-." She was soon cut off by Dorothea below.

"There has to be more than that. There's no way someone like you, a mo'o princess, would save a half-dead commoner siren on your own accord. Look, I know I sound a bit imperative and I'm sorry but I feel like there's a lot more you're hiding from me."

Once again, Petra fell silent. It wasn't like she was deliberately trying to hide her answer but it seemed more akin to her being nervous than anything. She continued to tell Dorothea her reasons.

"In Brigid there is a legend telling that the spirits will guide you to the one who will love you the most, your _hoa ora_. If you feel in your heart that both souls are compatible with one another, then a bond shall be created. When I was first seeing, no, when I first saw you, I felt something within me that I had never felt before. You were...so beautiful and I could not leave you to die. And then I realized, that _you_ were my mate of soul! That was why they guided me to you!" Petra soon leaped off of her tree-perch and dived into the crystal clear waters below her, landing seamlessly next to Dorothea. Dorothea however was still trying to process everything she said. She seemed so enthusiastic in her response, but the siren was just downright perplexed. 

"Can you... say that again please?" Dorothea asked, her voice somewhat shaking with nervousness. Another thing to notice about Dorothea's demeanor is that she was blushing beet red next to the mo'o noble and she didn't have a clue. Petra thought she was confused about her explanation, but no. The siren was baffled as to how hastily and eagerly she confessed her feelings towards her. 

"Do you not have understanding? I have already told you that you are my _hoa ora,_ but I am having apologies if all of this is sudden. It is tradition for my kin but I am not knowing if there is a similar custom in siren culture.” She replied, her voice sounding genuinely concerned about what she’d previously said to Dorothea. 

“No… I understand completely. If I truly am your soulmate, I’ll prove it.”

“There is nothing to be prove-“ Petra’s words were suddenly halted as Dorothea pressed her lips against hers in almost an instant. Unbeknownst to the siren, tears started to well up in her eyes and her heart began pounding out of her chest. The mo’o clenched Dorothea’s webbed hand while the siren gently caressed the vibrant scales on her face and braided hair, moving downward to her back. She had never felt this feeling in the open ocean. She’d only discovered this emotion when coming across Petra and nobody else. Dorothea didn’t believe in the concept of fate or soulmates initially, but their souls and spirits were already intertwined. In this solemn, tender moment in the crystal clear shallows, they were bound together. She didn’t want to let go of the mo’o’s embrace nor did she mind the coolness of the waters beneath them. Dorothea simply wanted this moment to last a lifetime.

“There is no one I would rather spend the rest of my days with than you, Petra. I am yours, forever and always.” She whispered softly.

“As am I. I am now thinking that it was not the will of the spirits that brought you here, but rather the tides of fate. And I am grateful for that.” 

“I love you, Petra.”

“ _ Aloha wau iā 'oe kekahi, fy hoa ora.”  _ Petra whispered back in her native tongue. They continued to hold each other even after the moment had passed, and now as they look towards the sun setting on the isles of Brigid, they think of a new dawn that will come to blossom between them. And Dorothea couldn’t have asked for anything more.

**Author's Note:**

> Hi there! I had a blast writing some good old fashioned creature fic with a bit of romance, and I really hope you enjoyed reading it as much as I did writing it.
> 
> Just a clarification about the types of mythological creatures Dorothea and Petra are supposed to be in this story:  
> Dorothea is obviously a siren, but she's a combination of the Greek interpretation (winged female creature with entrancing singing voice) and the modern-day interpretation of her somewhat resembling a mermaid. Some creative liberties had to be done for her character to make sense.  
> Petra is a mo’o, or Hawaiian dragon. They’re often portrayed as being spirits and guides of the sea, so once again it made sense to make her a mo’o because Brigid is seemingly inspired by many Polynesian cultures and also the fact that the first half of the story takes place in or near the ocean.  
> Also the line that Petra says in the end is Google translated from Hawaiian (because I'm too lazy to think of a whole conlang for Brigidian/Brigaeli/Brigaori) and it literally means "I love you too, my life partner"  
> -  
> Follow me on Twitter if you'd like to keep in touch and be the first to see drafts for other fics on @truthyyyyyyy


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